A meaningful investigation of unknown, unstructured datasets is still an unresolved issue. By and large in order to intelligently investigate unstructured datasets one needs to hold, in one way or the other a knowledge base of some sort (either knowledge of the world, logical structures, lexical dictionaries, etc.), or a set of rules, to lead the investigation.
There are two main difficulties one need to overcome required to automatically investigate an unstructured dataset: (1) how to apply the appropriate knowledge base when the dataset is unknown; (2) the dataset is known but the knowledge base is incomplete or obsolete.